146 E. T Quayle: 



which the river gains only negligible additions. These records began 

 in June, 1889. This weir appears to be the only interference with the 

 flow of the Avoca River, the waters of which have never been seriously^ 

 used for irrigation. The basin is, therefore, very suitable for such a 

 study as the present one. 



Summer and Minimum Flow Improving. 



Inspection of the data published by the Water Commission shows 

 a remarkable change in the constancy of the flow of the river. If 

 we compare the records for the twenty years, 1890-1909 inclusive, with 

 those for the ten years, 1910-1919, we find that in the former period 

 the river actually had no flow or ceased to run in 79 months; that it, 

 there were 79 months during the whole or a part of which there was 

 no discharge at Coonooer Weir, or at all events nothing more than, 

 the leakage which does not exceed one-sixth of a cubic foot per second. 

 During the decade 1910-19, the river has never ceased to flow, nor has 

 it done so up to the end of 1921. A comparison of the two great 

 drought years, 1902 and 1914, is equally instructive. Though the 

 latter was the more severe the river flow never fell below 5 cubic feet 

 per second, whereas in 1902 there were seven months during which 

 the river never ran at all. 



The following table shows the average minimum flow in cubic feet 

 per second for all months for the twenty years, 1890-1909, and for the 

 ten years, 1910-1919: — 



1890-1909. 



Jan. Feb. Mar. Apl. Ma}'. June. July. Auff. Sept.. Oct. Nov. Dec. Avg 

 1-4 - 0-65 - 1-0 - 1-2 - 1-8 - 7-3 - 16-1 - 247 - IS"! - 107 - 6-0 - 3-0 - 7-6 



1910-1919. 

 8-3 - 7-5 - 8-7 - 8-6 - 86 - 88 - 30-8 - 293 - 33-5 - 272 - 153 - 9'1 - 16-3- 



This shows that^during the summer half of the year, November- 

 April, the average minimum is now from two to ten times as great as 

 formerly, and is also considerably greater during the winter half. 

 That this is not due to any marked increase in the frequency of flood 

 rains is shown from the records of Amphitheatre, Avoca, Stuart Mill, 

 Emu and St. Arnaud. Taking all the occasions when the mean of the 

 daily rainfalls at these stations has equalled or exceeded 50 points, or 

 for two consecutive days 75 points, we get the following: — 





5 



i 



o 



3 



"5. 





4> 



S 

 3 





be 



3 

 < 



a. 

 en 



8 



o 





1 



1890-1909 - 



- 6 



- 5 - 



13 - 



16 - 



16 ■ 



26 - 



16 - 



10 - 



10 - 



10 



- 9 - 



8 - 



145 



1910-1919 - 



- 2 



8 - 



7 - 



4 - 



9 - 



12 - 



10 - 



7 - 



11 - 



5 



- 3 . 



7 - 



85 



Here the total "flood falls" for the summer halves are 57 for 

 the former and 31 for* the latter, and for the winter halves 88 and 54,. 

 showing clearly enough that it is not to any special increase in the 



